In recent years, for example, an organic EL (electroluminescence) display device including an organic EL element and a liquid crystal display device have been widely used for a television receiver, a monitor, a mobile phone, or a tablet as a flat panel display with features such as a smaller thickness and a lighter weight as compared with the conventional cathode ray tubes.
The above-described display device is provided with a display portion that displays information such as characters and images.
Furthermore, as the above-described display device, a flexible display device configured to be bendable has been developed and put into practical use, enabling information display to be performed by a display portion in a bent state. That is, a display device including such a display portion includes a flexible substrate, and a display element portion that is provided on the substrate and is provided to form the display portion. This display device is configured to allow the substrate to be bent in a state in which an organic EL layer or a liquid crystal layer, or a switching element such as a thin film transistor that are included in the display element portion are placed on the substrate.
In the above-described conventional display device, a TFT layer provided with the above-described display element portion such as a thin film transistor is bonded to a flexible substrate, with two layers, namely, a commonly used adhesive material layer and an adhesive material layer including glass fibers interposed therebetween, as described in Patent Document 1 below, for example. Then, this conventional display device is intended to reduce the bending stress and the stress due to thermal expansion that act on the TFT layer, thus achieving high reliability.